Reservoir host

A reservoir host is the species (or set of species) in which a pathogen persists in nature. Reservoirs typically carry the pathogen asymptomatically — the relationship is well-adapted enough that the host suffers little or no disease, even while continuously shedding virus. Humans are not reservoirs for most zoonotic pathogens; we are accidental hosts whose infection is a transmission dead-end (or, occasionally, the beginning of person-to-person spread).

Identifying the reservoir host is often the central question in early outbreak investigation. The reservoir for SARS-CoV-2 has been linked to bats with strong evidence and to one or more intermediate hosts with weaker evidence. The reservoir for Ebola virus is suspected to be fruit bats of family Pteropodidae, though definitive viral isolation from wild bats has been elusive. Hantaviruses each have a tightly specific rodent reservoir — Sin Nombre virus in deer mice, Puumala virus in bank voles, Hantaan virus in striped field mice, Andes virus in long-tailed pygmy rice rats.

Reservoir identification matters operationally because it informs where surveillance, prevention, and intervention efforts go. Removing the reservoir is rarely feasible; managing the human-reservoir interface (rodent-proof grain storage for hantavirus; bushmeat regulation for Ebola; bat-roost relocation in selected settings) is the standard public-health lever. The One Health framework explicitly aims to integrate human, animal, and environmental surveillance to detect spillover events earlier.